The invention relates to the field of water purification by degassing and distilling to remove dissolved gases and solids from the water.
Many areas of the world have serious water contamination and pollution problems of either a natural or man-created origin. Parts of the American West and other areas throughout the globe have water carrying high levels of sulphur dioxide, hydrogen sulfide and various other gases and minerals which make the water, at best, unpalatable and at times render it wholly unsuitable for drinking except after expensive purification measures. Other coastal areas have extensive supplies of readily available sea water but little fresh water. Still other regions have water supplies which have become so polluted by chemical wastes that extensive purification is needed before such water is again fit for human consumption. The present invention is directed toward the purification of such water and provides a workable, economical, solution for many of these contamination and pollution problems.
Typically, the purification of water can involve three distinct stages. One stage includes the use of distillation for the removal of dissolved solids contained in the water. Another stage of purification removes gases dissolved in the water which could pass through the distillation process. Accordingly, the degasification stage is best conducted prior to distillation. While these two stages are adequate in many purification processes, where high water purity is required it can also be desirable to remove charged ions, which if not removed by other means, can pass through the distillation process. Such ion removal can be highly desirable in order to produce the high levels of water purity needed in various medical applications and for research.
Since many purification projects require large volume water outputs, it is important that the purification process be accomplished with high energy efficiency and that minimal energy be required to support the purification operation.
Water purification through distillation is well recognized, and it is also known to utilize a lowered atmospheric pressure over a body of water so as to degasify the water; such a degasficiation system is shown in U.S. Pat. No. 4,407,665. It is also known to operate a degasification device in conjunction with a distillation system to use lowered atmospheric pressure in a distillation apparatus so as to lower the boiling point of the water to more quickly and inexpensively evaporate the water at lowered temperatures with less energy consumption. The present invention takes the degasification and distillation purification processes further in providing an apparatus which utilizes energy which is otherwise lost in the degasification process to assist the subsequent distillation step.